The invention relates to a process for producing a copper ceramic substrate with at least one through plated hole.
Producing a metal coating on a ceramic is known, for example on an aluminum oxide ceramic using the DCB (direct copper bond technology) process. This type of coating is required for the production of printed conductors, terminals, etc. Metal or copper foils, or metal or copper sheets, which form the substrate coating on the desired device, are applied as a coating (fusing layer) composed of a chemical compound of the metal and a reactive gas, preferably oxygen onto a side of the device's substrate. In this process, described for example in U.S. Pat. No. 37 44 120 or in DE-PS 23 19 854, this layer or this coating (fusing layer) forms a eutectic with a melting point below the melting point of the metal (for example, copper) so that by placing a foil on the ceramic and by heating all the layers they can be joined to one another by fusing the metal or copper exclusively in the area of the fusing layer, or the oxide layer.
This DCB process includes the following process steps:
oxidation of a copper foil such that a uniform copper layer results; PA1 placing a copper foil on the ceramic layer; PA1 heating the composite to a process temperature between roughly 1065 to 1083.degree. C., for example to roughly 1071.degree. C.; PA1 cooling to room temperature;
The object of the invention is to provide a process with which it is possible to produce metal-ceramic substrates for electrical circuits economically and reliably, with at least one through-plated hole.